/*
* Copyright (C) 2013 Nivis LLC.
* Email:   opensource@nivis.com
* Website: http://www.nivis.com
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 3 of the License.
* 
* Redistribution and use in source and binary forms must retain this
* copyright notice.

* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
*/

#include <sys/types.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <crypt.h>
#include <sys/cdefs.h>

/* MD5 context. */
struct MD5Context {
  u_int32_t state[4];   /* state (ABCD) */
  u_int32_t count[2];   /* number of bits, modulo 2^64 (lsb first) */
  unsigned char buffer[64];     /* input buffer */
};

static void   __md5_Init (struct MD5Context *);
static void   __md5_Update (struct MD5Context *, const unsigned char *, unsigned int);
static void   __md5_Pad (struct MD5Context *);
static void   __md5_Final (unsigned char [16], struct MD5Context *);
static void __md5_Transform (u_int32_t [4], const unsigned char [64]);


static const unsigned char __md5__magic[] = "$1$";      /* This string is magic for this algorithm.  Having
                                                   it this way, we can get better later on */
static const unsigned char __md5_itoa64[] =             /* 0 ... 63 => ascii - 64 */
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";


#ifdef i386
#define __md5_Encode memcpy
#define __md5_Decode memcpy
#else /* i386 */

/*
 * __md5_Encodes input (u_int32_t) into output (unsigned char). Assumes len is
 * a multiple of 4.
 */

static void
__md5_Encode (unsigned char *output, u_int32_t *input, unsigned int len)
{
        unsigned int i, j;

        for (i = 0, j = 0; j < len; i++, j += 4) {
                output[j] = (unsigned char)(input[i] & 0xff);
                output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
                output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
                output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
        }
}

/*
 * __md5_Decodes input (unsigned char) into output (u_int32_t). Assumes len is
 * a multiple of 4.
 */

static void
__md5_Decode (u_int32_t *output, const unsigned char *input, unsigned int len)
{
        unsigned int i, j;

        for (i = 0, j = 0; j < len; i++, j += 4)
                output[i] = ((u_int32_t)input[j]) | (((u_int32_t)input[j+1]) << 8) |
                    (((u_int32_t)input[j+2]) << 16) | (((u_int32_t)input[j+3]) << 24);
}
#endif /* i386 */

/* F, G, H and I are basic MD5 functions. */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/*
 * FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
 * Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac) { \
        (a) += F ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
        (a) = ROTATE_LEFT ((a), (s)); \
        (a) += (b); \
        }
#define GG(a, b, c, d, x, s, ac) { \
        (a) += G ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
        (a) = ROTATE_LEFT ((a), (s)); \
        (a) += (b); \
        }
#define HH(a, b, c, d, x, s, ac) { \
        (a) += H ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
        (a) = ROTATE_LEFT ((a), (s)); \
        (a) += (b); \
        }
#define II(a, b, c, d, x, s, ac) { \
        (a) += I ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
        (a) = ROTATE_LEFT ((a), (s)); \
        (a) += (b); \
        }

/* MD5 initialization. Begins an MD5 operation, writing a new context. */

static void __md5_Init (struct MD5Context *context)
{
        context->count[0] = context->count[1] = 0;

        /* Load magic initialization constants.  */
        context->state[0] = 0x67452301;
        context->state[1] = 0xefcdab89;
        context->state[2] = 0x98badcfe;
        context->state[3] = 0x10325476;
}

/*
 * MD5 block update operation. Continues an MD5 message-digest
 * operation, processing another message block, and updating the
 * context.
 */

static void __md5_Update ( struct MD5Context *context, const unsigned char *input, unsigned int inputLen)
{
        unsigned int i, idx, partLen;

        /* Compute number of bytes mod 64 */
        idx = (unsigned int)((context->count[0] >> 3) & 0x3F);

        /* Update number of bits */
        if ((context->count[0] += ((u_int32_t)inputLen << 3))
            < ((u_int32_t)inputLen << 3))
                context->count[1]++;
        context->count[1] += ((u_int32_t)inputLen >> 29);

        partLen = 64 - idx;

        /* Transform as many times as possible. */
        if (inputLen >= partLen) {
                memcpy((void *)&context->buffer[idx], (const void *)input,
                    partLen);
                __md5_Transform (context->state, context->buffer);

                for (i = partLen; i + 63 < inputLen; i += 64)
                        __md5_Transform (context->state, &input[i]);

                idx = 0;
        }
        else
                i = 0;

        /* Buffer remaining input */
        memcpy ((void *)&context->buffer[idx], (const void *)&input[i],
            inputLen-i);
}

/*
 * MD5 padding. Adds padding followed by original length.
 */

static void __md5_Pad ( struct MD5Context *context)
{
        unsigned char bits[8];
        unsigned int idx, padLen;
        unsigned char PADDING[64];

        memset(PADDING, 0, sizeof(PADDING));
        PADDING[0] = 0x80;

        /* Save number of bits */
        __md5_Encode (bits, context->count, 8);

        /* Pad out to 56 mod 64. */
        idx = (unsigned int)((context->count[0] >> 3) & 0x3f);
        padLen = (idx < 56) ? (56 - idx) : (120 - idx);
        __md5_Update (context, PADDING, padLen);

        /* Append length (before padding) */
        __md5_Update (context, bits, 8);
}

/*
 * MD5 finalization. Ends an MD5 message-digest operation, writing the
 * the message digest and zeroizing the context.
 */

static void __md5_Final ( unsigned char digest[16], struct MD5Context *context)
{
        /* Do padding. */
        __md5_Pad (context);

        /* Store state in digest */
        __md5_Encode (digest, context->state, 16);

        /* Zeroize sensitive information. */
        memset ((void *)context, 0, sizeof (*context));
}

/* MD5 basic transformation. Transforms state based on block. */

static void __md5_Transform (u_int32_t state[4], const unsigned char block[64])
{
        u_int32_t a, b, c, d, x[16];

#if MD5_SIZE_OVER_SPEED > 1
        u_int32_t temp;
        const char *ps;

        static const char S[] = {
                7, 12, 17, 22,
                5, 9, 14, 20,
                4, 11, 16, 23,
                6, 10, 15, 21
        };
#endif /* MD5_SIZE_OVER_SPEED > 1 */

#if MD5_SIZE_OVER_SPEED > 0
        const u_int32_t *pc;
        const char *pp;
        int i;

        static const u_int32_t C[] = {
                                                                /* round 1 */
                0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
                0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
                0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
                0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
                                                                /* round 2 */
                0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
                0xd62f105d, 0x2441453,  0xd8a1e681, 0xe7d3fbc8,
                0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
                0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
                                                                /* round 3 */
                0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
                0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
                0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x4881d05,
                0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
                                                                /* round 4 */
                0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
                0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
                0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
                0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
        };

        static const char P[] = {
                0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, /* 1 */
                1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12, /* 2 */
                5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2, /* 3 */
                0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9  /* 4 */
        };

#endif /* MD5_SIZE_OVER_SPEED > 0 */

        __md5_Decode (x, block, 64);

        a = state[0]; b = state[1]; c = state[2]; d = state[3];

#if MD5_SIZE_OVER_SPEED > 2
        pc = C; pp = P; ps = S - 4;

        for ( i = 0 ; i < 64 ; i++ ) {
                if ((i&0x0f) == 0) ps += 4;
                temp = a;
                switch (i>>4) {
                        case 0:
                                temp += F(b,c,d);
                                break;
                        case 1:
                                temp += G(b,c,d);
                                break;
                        case 2:
                                temp += H(b,c,d);
                                break;
                        case 3:
                                temp += I(b,c,d);
                                break;
                }
                temp += x[(int)(*pp++)] + *pc++;
                temp = ROTATE_LEFT(temp, ps[i&3]);
                temp += b;
                a = d; d = c; c = b; b = temp;
        }
#elif MD5_SIZE_OVER_SPEED > 1
        pc = C; pp = P; ps = S;

        /* Round 1 */
        for ( i = 0 ; i < 16 ; i++ ) {
                FF (a, b, c, d, x[(int)(*pp++)], ps[i&0x3], *pc++);
                temp = d; d = c; c = b; b = a; a = temp;
        }

        /* Round 2 */
        ps += 4;
        for ( ; i < 32 ; i++ ) {
                GG (a, b, c, d, x[(int)(*pp++)], ps[i&0x3], *pc++);
                temp = d; d = c; c = b; b = a; a = temp;
        }
        /* Round 3 */
        ps += 4;
        for ( ; i < 48 ; i++ ) {
                HH (a, b, c, d, x[(int)(*pp++)], ps[i&0x3], *pc++);
                temp = d; d = c; c = b; b = a; a = temp;
        }

        /* Round 4 */
        ps += 4;
        for ( ; i < 64 ; i++ ) {
                II (a, b, c, d, x[(int)(*pp++)], ps[i&0x3], *pc++);
                temp = d; d = c; c = b; b = a; a = temp;
        }
#elif MD5_SIZE_OVER_SPEED > 0
        pc = C; pp = P;

        /* Round 1 */
        for ( i = 0 ; i < 4 ; i++ ) {
                FF (a, b, c, d, x[(int)(*pp++)],  7, *pc++);
                FF (d, a, b, c, x[(int)(*pp++)], 12, *pc++);
                FF (c, d, a, b, x[(int)(*pp++)], 17, *pc++);
                FF (b, c, d, a, x[(int)(*pp++)], 22, *pc++);
        }

        /* Round 2 */
        for ( i = 0 ; i < 4 ; i++ ) {
                GG (a, b, c, d, x[(int)(*pp++)],  5, *pc++);
                GG (d, a, b, c, x[(int)(*pp++)],  9, *pc++);
                GG (c, d, a, b, x[(int)(*pp++)], 14, *pc++);
                GG (b, c, d, a, x[(int)(*pp++)], 20, *pc++);
        }
        /* Round 3 */
        for ( i = 0 ; i < 4 ; i++ ) {
                HH (a, b, c, d, x[(int)(*pp++)],  4, *pc++);
                HH (d, a, b, c, x[(int)(*pp++)], 11, *pc++);
                HH (c, d, a, b, x[(int)(*pp++)], 16, *pc++);
                HH (b, c, d, a, x[(int)(*pp++)], 23, *pc++);
        }

        /* Round 4 */
        for ( i = 0 ; i < 4 ; i++ ) {
                II (a, b, c, d, x[(int)(*pp++)],  6, *pc++);
                II (d, a, b, c, x[(int)(*pp++)], 10, *pc++);
                II (c, d, a, b, x[(int)(*pp++)], 15, *pc++);
                II (b, c, d, a, x[(int)(*pp++)], 21, *pc++);
        }
#else
        /* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
        FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
        FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
        FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
        FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
        FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
        FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
        FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
        FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
        FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
        FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
        FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
        FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
        FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
        FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
        FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
        FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

        /* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
        GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
        GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
        GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
        GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
        GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
        GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
        GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
        GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
        GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
        GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
        GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
        GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
        GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
        GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
        GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
        GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

        /* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
        HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
        HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
        HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
        HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
        HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
        HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
        HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
        HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
        HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
        HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
        HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
        HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
        HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
        HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
        HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
        HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */

        /* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
        II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
        II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
        II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
        II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
        II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
        II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
        II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
        II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
        II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
        II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
        II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
        II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
        II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
        II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
        II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
        II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
#endif

        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;

        /* Zeroize sensitive information. */
        memset ((void *)x, 0, sizeof (x));
}


static void __md5_to64( char *s, unsigned long v, int n)
{
        while (--n >= 0) {
                *s++ = __md5_itoa64[v&0x3f];
                v >>= 6;
        }
}

/*
 * UNIX password
 *
 * Use MD5 for what it is best at...
 */

char *md5_crypt(const char *pw, const char *salt, char*passwd)
{
        /* Static stuff */
        /*static*/ const char *sp, *ep;
        char *p;

        unsigned char   final[17];      /* final[16] exists only to aid in looping */
        int sl,pl,i,__md5__magic_len,pw_len;
        struct MD5Context ctx,ctx1;
        unsigned long l;

        /* Refine the Salt first */
        sp = salt;

        /* If it starts with the magic string, then skip that */
        __md5__magic_len = strlen((const char*)__md5__magic);
        if(!strncmp(sp,(const char*)__md5__magic,__md5__magic_len))
                sp += __md5__magic_len;

        /* It stops at the first '$', max 8 chars */
        for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
                continue;

        /* get the length of the true salt */
        sl = ep - sp;

        __md5_Init(&ctx);

        /* The password first, since that is what is most unknown */
        pw_len = strlen(pw);
        __md5_Update(&ctx,(const unsigned char*)pw,pw_len);

        /* Then our magic string */
        __md5_Update(&ctx,__md5__magic,__md5__magic_len);

        /* Then the raw salt */
        __md5_Update(&ctx,(const unsigned char*)sp,sl);

        /* Then just as many characters of the MD5(pw,salt,pw) */
        __md5_Init(&ctx1);
        __md5_Update(&ctx1,(const unsigned char*)pw,pw_len);
        __md5_Update(&ctx1,(const unsigned char*)sp,sl);
        __md5_Update(&ctx1,(const unsigned char*)pw,pw_len);
        __md5_Final(final,&ctx1);
        for(pl = pw_len; pl > 0; pl -= 16)
                __md5_Update(&ctx,final,pl>16 ? 16 : pl);

        /* Don't leave anything around in vm they could use. */
        memset(final,0,sizeof final);

        /* Then something really weird... */
        for (i = pw_len; i ; i >>= 1) {
                __md5_Update(&ctx, ((i&1) ? final : (const unsigned char *) pw), 1);
        }

        /* Now make the output string */
        strcpy(passwd,(const char*)__md5__magic);
        strncat(passwd,(const char*)sp,sl);
        strcat(passwd,"$");

        __md5_Final(final,&ctx);

        /*
         * and now, just to make sure things don't run too fast
         * On a 60 Mhz Pentium this takes 34 msec, so you would
         * need 30 seconds to build a 1000 entry dictionary...
         */
        for(i=0;i<1000;i++) {
                __md5_Init(&ctx1);
                if(i & 1)
                        __md5_Update(&ctx1,(const unsigned char*) pw,pw_len);
                else
                        __md5_Update(&ctx1,final,16);

                if(i % 3)
                        __md5_Update(&ctx1,(const unsigned char*)sp,sl);

                if(i % 7)
                        __md5_Update(&ctx1,(const unsigned char*)pw,pw_len);

                if(i & 1)
                        __md5_Update(&ctx1,final,16);
                else
                        __md5_Update(&ctx1,(const unsigned char*)pw,pw_len);
                __md5_Final(final,&ctx1);
        }

        p = passwd + strlen(passwd);

        final[16] = final[5];
        for ( i=0 ; i < 5 ; i++ ) {
                l = (final[i]<<16) | (final[i+6]<<8) | final[i+12];
                __md5_to64(p,l,4); p += 4;
        }
        l = final[11];
        __md5_to64(p,l,2); p += 2;
        *p = '\0';

        /* Don't leave anything around in vm they could use. */
        memset(final,0,sizeof final);

        return passwd;
}
